History

The first inspiration for cluster computing was developed in the 1960s by IBM as an alternative of linking

large mainframes to provide a more cost effective form of commercial parallelism

A cluster is a type of parallel or distributed computer system, which consists of a collection of inter-connected stand-alone computers working together as a single integrated computing resource

IT or information technology departments are constantly looking for ways to make their computers produce the maximum processing power. Usually the departments are working under limited or restricted budgets. However, many companies are asking that these departments provide large amounts of this processing power to meet their needs in terms of applications, knowledge management, databases and more.

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Introduction

Definition

Cluster computing is the technique of linking two or more computers into a network (usually through a local area network) in order to take advantage of the parallel processing power of those computers.

The components of a cluster are commonly, but not always, connected to each other through fast local area network.

Clusters are usually deployed to improve performance and availability over that of a single computer, while typically being much more costeffective than single computers of comparable speed or availability. Cluster computing provides a number of advantages with respect to conventional custom-made parallel computers for achieving performance greater than that typical type of uniprocessors.

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As a consequence, the emergence of clusters has greatly extended the availability of high performance processing to a much broader community and advanced its impact through new opportunities in science, technology, industry, medical, commercial, finance, defense, and education among other sectors of computational application. Included among the most significant advantages

Consists of many of the same or similar type of machines Tightly-coupled using dedicated network connections All machines share resources such as a common home directory Must have software such as an MPI implementation installed to allow programs to be run across all nodes

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Architecture

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Components

The components which require to make cluster computing that critical to the development of low cost cluster are:

1. High Availability Clusters (HA cluster)

High Availability Clusters are designed to ensure constant access to service applications.

The clusters are designed to maintain redundant nodes that can act as backup system in the event of failure.

The minimum number of nodes in a HA cluster is two one active and one redundant though most HA clusters will use considerably more nodes.

Fig of HA cluster

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2. Load-balancing Clusters

Load-balancing clusters operate by routing all work through one or more load-balancing front-end nodes, which then distribute the workload efficiently between the remaining active nodes.

Load-balancing clusters are extremely useful for those working with limited IT budgets. Devoting a few nodes to managing the workflow of a cluster ensures that limited processing power can be optimised.

3. High-performance Clusters(HPC cluster)

HPC clusters are designed to exploit the parallel processing power of multiple nodes.

They are most commonly used to perform functions that require nodes to communicate as they perform their tasks for instance, when calculation results from one node will affect future results from another.

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Benefits of Cluster computing

Computer clusters offer a number of benefits over mainframe computers, including:

Reduced Cost

Processing Power

Improved Network Technology

Scalability

Availability

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1. Reduced Cost:

The price of off-the-shelf consumer desktops has plummeted in recent years, and this drop in price has corresponded with a vast increase in their processing power and performance.

The average desktop PC today is many times more powerful than the first mainframe computer

2. Processing Power :

The parallel processing power of a high-performance cluster can, in many cases, prove more cost effective than a mainframe with similar power.

This reduced price per unit of power enables enterprises to get a greater ROI from their IT budget.

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3. Improved Network Technology:

Driving the development of computer clusters has been a vast improvement in the technology related to networking, along with a reduction in the price of such technology.

Computer clusters are typically connected via a single virtual local area network (VLAN), and the network treats each computer as a separate node. Information can be passed throughout these networks with very little lag, ensuring that data doesnt bottleneck between nodes.

4. Scalability: Perhaps the greatest advantage of computer clusters is the scalability they offer. While mainframe computers have a fixed processing capacity, computer clusters can be easily expanded as requirements change by adding additional nodes to the network.

5. Availability: When a mainframe computer fails, the entire system fails. However, if a node in a computer cluster fails, its operations can be simply transferred to another node within the cluster, ensuring that there is no interruption in service.

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Challenges

The cluster computing concept also poses three pressing research challenges:

A cluster should be a single computing resource and provide a single system image. This is in contrast to a distributed system where the nodes serve only as individual resources.

The supporting operating system and communication Mechanism must be efficient enough to remove the performance Bottlenecks.

It must provide scalability by letting the system scale up or down. The scaled-up system should provide more functionality or better performance. The systems total computing power should increase proportionally to the increase in resources. The main motivation for a scalable system is to provide a flexible, cost effective Informationprocessing tool.